1. Field of the Invention
The present invention generally relates to a microwave oven and a control method thereof. More particularly, the present invention relates to a microwave oven with its convenience being improved by suitably controlling movement of a member mounted thereto, and a control method thereof.
2. Description of the Background Art
As described in Japanese Laid-Open Publication Nos. 8-145376 and 9-72549, some of the conventional microwave ovens are provided with an infrared sensor capable of detecting the temperature of a food within a heating chamber. Note that this infrared sensor is capable of including a part of the heating chamber in its field of view, and also capable of moving the field of view. Accordingly, wherever the food is placed in the heating chamber, the infrared sensor can include the food in the field of view, and thus can detect the temperature of the food.
However, the conventional microwave ovens move the field of view of the infrared sensor first from a corner of the heating chamber. In general, the food is often placed in the central region of the heating chamber. Therefore, cooking of the food may be completed before the food is included in the field of view of the infrared sensor. In other words, the conventional microwave ovens may not be able to use the detection result of the infrared sensor for cooking, resulting in degraded convenience.
Moreover, in order to move the field of view of the infrared sensor in such a manner as described above, the infrared sensor is conventionally moved with a motor. However, the field of view of the infrared sensor may not be able to be moved to a correct position due to the problems of such a moving mechanism itself. This will be described with reference to FIGS. 18 and 19. FIGS. 18 and 19 are diagrams illustrating the problems of the moving mechanism using a motor.
FIG. 18 is a diagram showing a gear that rotates according to operation of the motor (motor-side gear 200) and a gear that is fixed to the infrared sensor (sensor-side gear 100). The motor-side gear 200 is rotatable in the rotation direction H1 or H2. When the motor-side gear 200 is driven by the motor to rotate in the rotation direction H1, the sensor-side gear 100 rotates in the rotation direction J1 accordingly. When the motor-side gear 200 rotates in the rotation direction H2, the sensor-side gear 100 rotates in the rotation direction J2 accordingly. In response to the rotation of the sensor-side gear 100 in the rotation direction J1 or J2, the infrared sensor is moved, so that the field of view thereof is moved.
Note that the movement distance of the infrared sensor is controlled by controlling the rotation distance of the motor-side gear 200.
FIG. 19 is an enlarged view of an engaged tooth portion of the two gears shown in FIG. 18. There is a clearance B between a tooth of the motor-side gear 200 and a tooth of the sensor-side gear 100 engaged therewith. Note that the two gears are rotatable, namely, are not fixed. Accordingly, the clearance between the engaged teeth is not always constant at B. In other words, the clearance is produced only under the tooth of the sensor-side gear 100 in FIG. 19, but such a clearance may be produced both above and under the tooth of the sensor-side gear 100.
Provided that the clearance between the tooth of the motor-side gear 200 and the tooth of the sensor-side gear 100 engaged therewith is not constant, the motor-side gear 200 does not rotate by a constant distance from the start of its rotation until the rotation force thereof is transmitted to the sensor-side gear 100.
In other words, even if the rotation distance of the motor-side gear 200 is accurately controlled, the movement distance of the infrared sensor cannot be controlled accurately.
Therefore, the conventional microwave ovens may not be able to move the field of view of the infrared sensor by an accurate distance. As a result, the conventional microwave ovens may not be able to include the food within the heating chamber in the field of view of the infrared sensor, resulting in degraded convenience.
Moreover, in order to demonstrate features of the microwave oven at the stores or the like, the conventional microwave ovens have a demonstration function to rotate a turntable and display the remaining cooking time without conducting the heating operation. The conventional microwave ovens provided with the infrared sensor are capable of causing the infrared sensor to detect a temperature without conducting the heating operation as a demonstration.
However, such a demonstration of temperature detection by the infrared sensor in the conventional microwave ovens is conducted with the field of view of the infrared sensor being fixed in position. Therefore, the conventional microwave ovens cannot demonstrate the ability to detect the temperature of the food regardless of the position of the food within the heating chamber, resulting in degraded convenience.
Moreover, some of the conventional microwave ovens are provided with a rotating antenna in order to diffuse microwaves oscillated by a magnetron. This rotating antenna is rotatable. However, the conventional microwave ovens cannot rotate the rotating antenna that directly relates to the heating operation of the magnetron in the demonstration, resulting in degraded convenience.
The present invention is made in view of the above, and it is an object of the present invention to provide a microwave oven with improved convenience by causing a member for moving a field of view of an infrared sensor to move in an appropriate manner.
It is another object of the present invention to provide a microwave oven with improved convenience by causing a member for moving a field of view of an infrared sensor to move in an appropriate manner when conducting a demonstration.
It is still another object of the present invention to provide a microwave oven with improved convenience by causing a rotating antenna to move in an appropriate manner when conducting a demonstration.
According to one aspect of the present invention, a microwave oven is characterized in that it includes a heating chamber for accommodating an object, an infrared sensor having a field of view within the heating chamber, for detecting a temperature of the object in the heating chamber, and a field-of-view moving portion for moving the field of view of the infrared sensor. Note that the field-of-view moving portion moves the field of view in a central region of the heating chamber when temperature detection by the infrared sensor is started in the microwave oven.
According to the present invention, a food can be more quickly included in the field of view of the infrared sensor when being placed in the central region of the heating chamber.
In the microwave oven, the food is often placed in the central region of the heating chamber. Therefore, in such a case, the food can be more quickly included in the field of view. In other words, heating of the food is less likely to be completed before the food is included in the field of view of the infrared sensor. As a result, convenience of the microwave oven can be improved.
Preferably, the microwave oven according to the present invention further includes a presence determination portion for determining whether or not the object is present within the field of view of the infrared sensor, based on a detection result of the infrared sensor. The field-of-view moving potion preferably extends a movement range of the field of view to a range broader than the central region of the heating chamber, if the presence determination portion determines that the object is not present in the central region of the heating chamber.
As a result, the food can be included in the field of view of the infrared sensor even when being placed in a position other than the central region of the heating chamber.
Preferably, the microwave oven according to the present invention further includes a presence determination portion for determining whether or not the object is present within the field of view of the infrared sensor, based on a detection result of the infrared sensor, a heating portion for heating the object in the heating chamber, and a control portion for controlling the heating operation of the heating portion. If the presence determination portion determines that the object is not present in the central region of the heating chamber, the control portion preferably discontinues the heating operation of the heating portion right after the movement of the field of view in the central region of the heating chamber is completed, or after a predetermined time has passed since the movement of the field of view in the central region of the heating chamber is completed.
As a result, the heating can be prevented from being conducted despite the fact that no food is placed in the heating chamber.
In the microwave oven according to the present invention, the field-of-view moving portion preferably starts moving the field of view when the heating operation of the heating portion is started. When the field-of-view moving portion extends the movement range of the field of view to the range broader than the central region of the heating chamber, the control portion preferably reduces a heating output of the heating portion from a value that was used during movement of the field of view in the central region of the heating chamber. In this case, the reduced heating output is used until the presence determination portion determines that the object is present.
As a result, over-heating of the food can be prevented as much as possible when scanning of the field of view must be conducted for a long time in order to detect the position of the food. Moreover, in the case where no food is likely to be placed in the heating chamber, a wasteful heating operation can be suppressed. This is because, in the microwave oven, the food is often placed in the central region of the heating chamber.
Preferably, the microwave oven according to the present invention further includes a movement instruction portion for sending the field-of-view moving portion an instruction of whether to move the field of view or not, a movement determination portion for determining whether the field of view is being moved or not, and a notifying portion for notifying if a determination result of the movement determination portion is different from the instruction sent from the movement instruction portion to the field-of-view moving portion.
As a result, such a problematic situation of the microwave oven that the food cannot be included the field of view due to inability to control the moving manner of the field of view of the infrared sensor can be solved in an early stage.
In the microwave oven according to the present invention, the control portion preferably discontinues the heating operation of the heating portion in response to the notification from the notifying portion.
As a result, the heating portion can be prevented from continuing the heating operation in such a dangerous situation that a member of the microwave oven malfunctions.
According to another aspect of the present invention, a microwave oven is characterized in that it includes a heating chamber for accommodating an object, an infrared sensor having a field of view within the heating chamber, for detecting a temperature of the object in the heating chamber, a motor for moving the infrared sensor in order to move the field of view, a sensor-side gear fixed to the infrared sensor, and a motor-side gear fixed to the motor, and engaged with the sensor-side gear, and in that the sensor-side gear is rotatable, and is biased in one of rotation directions of the sensor-side gear.
According to the present invention, the distance between a tooth of the motor-side gear and a tooth of the sensor-side gear can be made constant.
In other words, the motor-side gear always rotates by a constant distance from the start of its rotation until the tooth thereof is brought into contact with the tooth of the sensor-side gear for power transmission thereto. Accordingly, the relation between the driving amount of the motor and the movement amount of the field of view of the infrared sensor is stabilized. As a result, the field of view of the infrared sensor can be moved more accurately.
Preferably, in the microwave oven according to the present invention, the sensor-side gear is rotatable in one and the other of the rotation directions, and a rotation limit for moving the field of view is set in each of one and the other of the rotation directions of the sensor-side gear. The rotation limit for moving the field of view is a rotation limit to which the sensor-side gear can rotate in order to move the field of view. An origin of the field of view is preferably defined as a position corresponding to the sensor-side gear rotated to the rotation limit for moving the field of view in one of the rotation directions.
Accordingly, when the field of view of the infrared sensor is located at the origin, the sensor-side gear is biased in one of the rotation directions, and located at the rotation limit in one of the rotation directions.
In other words, when the field of view is located at the origin, the tooth of the sensor-side gear is in contact with the tooth of the motor-side gear, at the surface located in one of the rotation directions of the sensor-side gear. This is because the sensor-side gear is biased in one of the rotation directions. In order to move the field of view from the origin, the sensor-side gear is rotated in the other rotation direction. Therefore, the power of the motor-side gear is transmitted to the sensor-side gear from the moment the rotation of the motor-side gear is started. As a result, the movement distance of the field of view from the origin can be controlled accurately.
In the microwave oven according to the present invention, the sensor-side gear preferably has a physically rotatable range in at least one of the rotation directions. The physically rotatable range is a physical rotation range of the sensor-side gear itself. Preferably, a rotation range defined by the respective rotation limits for moving the field of view in one and the other of the rotation directions is included in, and is smaller than, the physically rotatable range.
As a result, the sensor-side gear can move the field of view with a margin of the rotation range.
According to still another aspect of the present invention, a microwave oven is characterized in that it includes a heating chamber for accommodating an object, a heating portion for heating the object in the heating chamber, an infrared sensor having a field of view within the heating chamber, for detecting a temperature of the object in the heating chamber, a field-of-view moving portion for moving the field of view of the infrared sensor, and a demo executing portion for conducting a demonstration in which the field of view is moved and the infrared sensor is caused to conduct the temperature detection without operating the heating portion.
According to the present invention, the field of view of the infrared sensor can be moved in the microwave oven even in the case of the demonstration.
Accordingly, the ability of the infrared sensor to move the field of view thereof and to detect a food temperature regardless of the position of the food within the heating chamber can be more easily demonstrated.
Preferably, the microwave oven according to the present invention further includes a temperature display portion for displaying a temperature detected by the infrared sensor. Preferably, the temperature display portion does not display the detected temperature while the field-of-view moving portion is moving the field of view.
As a result, confusing temperature display can be avoided that results from continuous temperature display during movement of the field of view.
Preferably, the microwave oven according to the present invention further includes a presence determination portion for determining whether or not the object is present within the field of view of the infrared sensor, based on a detection result of the infrared sensor. Preferably, the field-of-view moving portion fixes a position of the field of view to a position of the object as determined by the presence determination portion, and the temperature display portion displays a temperature detected by the infrared sensor with the position of the field of view fixed by the field-of-view moving portion.
As a result, the temperature of the object is displayed in response to determination that the object is present within the heating chamber.
Accordingly, if the object is present within the heating chamber, the field of view of the infrared sensor is automatically moved to the position of the object, and the temperature of the object is displayed.
In the microwave oven according to the present invention, the presence determination portion preferably determines that the object is present at a certain position if a temperature detected by the infrared sensor with the field of view moved to the certain position is different at least by a predetermined value from a temperature detected by the infrared sensor with the field of view moved to a position adjacent to the certain position.
As a result, detection of the position of the object can be facilitated.
According to yet another aspect of the present invention, a microwave oven is characterized in that it includes a heating chamber for accommodating an object, a magnetron for supplying microwaves into the heating chamber, and a rotating antenna for rotating during oscillation of the microwaves by the magnetron in order to diffuse the microwaves oscillated by the magnetron, and in that a demonstration of the rotating antenna is conducted in which the rotating antenna is rotated without causing the magnetron to oscillate the microwaves.
According to the present invention, the rotating antenna that directly relates to a heating operation can be rotated without conducting the heating operation (microwave oscillation operation).
Accordingly, characteristics of the rotating antenna itself such as its rotating manner in the microwave oven can be more easily demonstrated.
Preferably, the microwave oven according to the present invention further includes a non-heating member for conducting an operation different from a heating operation in the microwave oven, and a normal demonstration is conducted in which the operation of the non-heating member is conducted without causing the magnetron to oscillate the microwaves. The demonstration of the rotating antenna and the normal demonstration are preferably conducted independently of each other.
As a result, capability of the rotating antenna that directly relates to the heating operation can be more easily demonstrated.
Preferably, the microwave oven according to the present invention further includes a door for opening and closing the heating chamber. Preferably, the rotating antenna is visually recognized more clearly when the door is opened, and the non-heating member includes a member that is visually recognized more clearly when the door is opened. The demonstration of the rotating antenna and the normal demonstration are preferably conducted with the door being opened.
As a result, the two demonstrations can be move effectively conducted.
Preferably, the microwave oven according to the present invention further includes a predetermined operation portion that is operated by a user. The demonstration of the rotating antenna and the normal demonstration are preferably conducted in response to operation of the predetermined operation portion.
As a result, a required number of operation portions in the microwave oven can be reduced.
In the microwave oven according to the present invention, an operation time of the predetermined operation portion that is required to conduct the demonstration of the rotating antenna is preferably longer than that required to conduct the normal demonstration.
As a result, an operator""s interest in the demonstration of the rotating antenna that directly relates to the heating operation can be increased as compared to another demonstration.
In the microwave oven according to the present invention, a number of times to operate the predetermined operation portion that is required to conduct the demonstration of the rotating antenna is preferably larger than that required to conduct the normal demonstration.
As a result, an operator""s interest in the demonstration of the rotating antenna that directly relates to the heating operation can be increased as compared to another demonstration.
Preferably, the microwave oven according to the present invention further includes a counting portion for counting a number of times the predetermined operation portion is operated. The counting portion preferably initializes its count value if a predetermined time has passed since the predetermined operation portion was operated first.
As a result, unwanted execution of the demonstration of the rotating antenna resulting from leaving the operated predetermined operation portion can be avoided.
According to one aspect of the invention, a method for controlling a microwave oven is characterized in that a field of view of an infrared sensor is moved in a central region of a heating chamber when the infrared sensor is caused to start temperature detection of an object within the heating chamber.
According to the present invention, a food can be more quickly included in the field of view of the infrared sensor when being placed in the central region of the heating chamber.
In the microwave oven, the food is often placed in the central region of the heating chamber. Therefore, in such a case, the food can be more quickly included in the field of view. In other words, heating of the food is less likely to be completed before the food is included in the field of view of the infrared sensor. As a result, convenience of the microwave oven can be improved.
According to another aspect of the invention, a method for controlling a microwave oven including an infrared sensor having a field of view within a heating chamber for detecting a temperature of an object in the field of view is characterized in that the method includes the step of detecting the temperature of the object by detecting an amount of infrared radiation within the field of view while moving the field of view, and in that the field of view is moved by rotation of a predetermined gear, and a movement origin of the field of view is defined as a position corresponding to a rotation limit of the predetermined gear.
According to the present invention, the distance between a tooth of a motor-side gear and a tooth of a sensor-side gear can be made constant. When the field of view of the infrared sensor is located at the origin, the sensor-side gear is biased in one of its rotation directions, and located at its rotation limit in one of the rotation directions.
In other words, the motor-side gear always rotates by a constant distance from the start of its rotation until the tooth thereof is brought into contact with the tooth of the sensor-side gear for power transmission thereto. Accordingly, the relation between the driving amount of the motor and the movement amount of the field of view of the infrared sensor is stabilized. As a result, the field of view of the infrared sensor can be moved more accurately.
According to still another aspect of the present invention, a method for controlling a microwave oven in which temperature detection by an infrared sensor is conducted with a field of view of the infrared sensor being moved within a heating chamber is characterized in that a demonstration of the infrared sensor is conducted by causing the infrared sensor to conduct the temperature detection without conducting a heating operation of a heating portion.
According to the present invention, the field of view of the infrared sensor can be moved in the microwave oven as a demonstration without conducting the heating operation of the heating portion.
Accordingly, the ability of the infrared sensor to move the field of view thereof and to detect a food temperature regardless of the position of the food within the heating chamber can be more easily demonstrated.
According to yet another aspect of the present invention, a method for controlling a microwave oven is characterized in that a demonstration of a rotating antenna provided in the microwave oven in order to diffuse microwaves emitted from a magnetron is conducted by rotating the rotating antenna without causing the magnetron to oscillate the microwaves.
According to the present invention, the rotating antenna that directly relates to a heating operation can be rotated without conducting the heating operation (microwave oscillation operation).
Accordingly, characteristics of the rotating antenna itself such as its rotating manner in the microwave oven can be more easily demonstrated.
The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings.